Sinnoh Underground Guide

[Epithet]

 

Welcome to the comprehensive guide for the Sinnoh Underground. In this guide, you will be shown what you will need, how to complete it, and what rewards you can receive.

This daily task, the Sinnoh Underground, is a special area that can be accessed from Eterna City. In short, it is a puzzle-solving mini-game where the goal is to correctly guess the alignment of the crystals in as few guesses as possible. The rewards are directly tied to the amount of tries needed to solve the puzzle.

 

Preparations & Getting Started

In order to enter the underground area, you will have to make your way to Eterna City in the Sinnoh Region.

Once there, head into Eterna House 2, which is the house directly to the right of the Pokémon Center. Inside, you will find two NPCs, Explorer Morris and Explorer Stanley. Explorer Morris doesn't have much to say aside from some fluff dialog about the "new" puzzle, in reference to the update this daily task received in 2025; older players who remember how it was before may appreciate this callback.

Explorer Stanley is who you really want to talk to. At a fee of 3,000 Pokédollars, Stanley will grant you access to the Sinnoh Underground. But, before entering, some preparations should be made. 

 

To properly go through this in a smooth fashion, players should bring with them a Fire, Ground, Rock, and Water type Pokémon. A Grass type should also be taken if players are looking for the special area.

In addition to the Pokémon being of a certain type, the chosen Pokémon should also know the move Dig as well as have max (255) happiness points or you must have a Shovel in your inventory. Note that the task can be completed without any of these Pokémon and/or without the max happiness, but it is not guaranteed, and you may end up with an incorrect amount of crystals and thus, cannot finish the puzzle. You should also bring a Pokémon with Flash or a Flashlight.

This brings you to 5 Pokémon in your party. Since there will be catchable Pokémon in the rewards room, a Synchronize Pokémon of your choosing may be the best option to be your final slot. However, this can be any other Pokémon you wish to bring along.

After getting all your Pokémon ready, speak with Stanley, pay the entrance fee, and go on in.

 

Digging & Solving

 

Now that you're inside the underground area, you will notice a line of 7 little piles of rocks in the center, a column of 7 crystals along each side of the room, and four ladders that lead further down.

That row of rocks in the middle is where the puzzle is to be solved. By placing crystals in these slots, the puzzle will be solved. To know if the correct crystal was placed in the correct slot, you should look at the two columns of crystals on each side of the room. If, when you a place a crystal, the left side changes and matches with the column on the right, then it's a match and that's where that crystal goes. You continue this pattern until all 7 slots are full. Once that is done, then head to any dig hole on a wall, and you will be taken to the Treasure Room.

 

 

 

 

 

Alternatively, if you find the Grass Crystal and place it in the correct slot, then the Arboreal Area will be opened to you instead of the Treasure Room. To know what slot the Grass Crystal goes in, speak with Explorer Elena in Underground Path Sinnoh Room 2. She will mention a tablet with a number on it; that number reflects the slot you should place the Grass Crystal on, moving from left to right. Once inserted, you will receive dialog confirming it. After that, you should remove the Grass Crystal and finish the puzzle.

 

 

 

Now, how do you actually get crystals?

Pick a ladder and go down it. Once down there, it will be dark and you are advised to use Flash or a Flashlight. Now that everything is lit up, you will want to pay attention to two things: the dig holes on the walls and the Probopass. The dig holes are where you will find the crystals. There are 5 kinds of crystals, Fire, Ground, Rock, Water, and Grass.  The first 4 crystals are used to solve the normal puzzle and the Grass crystal is used to solve the hidden puzzle, which unlocks the Arboreal Area. 

 

To gather the crystals needed to solve the puzzle, you will need to use Dig or a Shovel on the dig holes. Using a Pokémon that matches the type of a crystal will give you a crystal of said type. For example, using a Ground type Pokémon with Dig and max happiness will grant you a Ground Crystal. However, using a Shovel, a Pokémon with less than maximum happiness, or a Pokémon that does not match the type will grant a random crystal. Continue to do this until you find enough crystals to solve the puzzle.

 

As for the Grass Crystal, the way to know if the dig hole will have it is by battling the Probopass. Every Probopass will use either Iron Defense or Body Press. However, there will be one Probopass that will use Explosion; this Probopass is the indicator that the nearby dig hole has the Grass Crystal.

Now, with all the crystals gathered, head back to the main room and begin solving the puzzle. Refer to the previous paragraph for instructions on how to solve it.

Once solved, and depending on whether you used the Grass Crystal or not, you can head to the rewards room. 

 

 

 

 

 

Rewards

After solving the normal puzzle, you can dig through any of the holes on the walls to enter the Treasure Room.

But, if you have solved the hidden puzzle with the Grass Crystal, you can head to the dig hole where you obtained the Grass Crystal and dig there. Doing so will lead you to the Arboreal Area. 

 

Treasure Room

Each line below represents a possible reward you can pick up.

◆  Any of the fossils (Dome, Helix, Old Amber, Root, Claw, Armor, Skull, Jaw, Sail) ◆

◆ Earthquake or Scorching Sands TM ◆

◆ Stone Edge, Meteor Beam, or Stealth Rock TM ◆

◆ Pearl or Nugget ◆

◆ Big Pearl or Big Nugget ◆

◆ Upgrade or Dubious Disc ◆

◆ Protector, Razor Fang, or Razor Claw ◆

 

Arboreal Area

◆ 3-5 PvE Coins ◆

◆ x1 Trailblaze, Earth Power, or Aura Sphere TM ◆

◆ 0-2 Tiny Mushrooms from 11 of the Mushroom tiles on the map ◆

◆ Up to 2 Teddiursa, each holding a Peat Block ◆

◆ Up to 3 Voltorb-Hisui ◆

◆ Up to 1 Growlithe-Hisui ◆

◆ Up to 2 Scyther, each holding a Black Augurite ◆